Exploring micro(nano)plastic presence and effects in human airways: in vitro and clinical findings

Airborne micro(nano)plastics (MNPs), as a part of air pollution, have become a growing concern worldwide, with the potential to cause adverse effects on the human respiratory system. Although MNPs are abundant in the atmosphere, there is limited data regarding their deposition and biological effects on the human airways and lungs. Therefore, this study aimed to investigate the presence of MNPs in the clinical samples of bronchoalveolar lavage fluid (BALF) of living patients and MNPs9 biological effect on human cells in vitro. Optical and transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (TEM-EDX) was used to detect, quantify, and analyze the MNPs in BALF samples. In parallel, human bronchial epithelial cells, BEAS-2B, were exposed to different concentrations of MNPs for up to 48 hours, and intracellular MNP accumulation, cell viability, morphology, and metabolic response were evaluated. Our results revealed that all tested BALF samples were positive for MNP presence, predominantly in fragmented shape and in the interval of 0.14 - 12.8 particles per 100 ml of BALF. Additionally, the in vitro exposure study showed that accumulation of MNPs inside bronchial epithelial cells leads to reduced cell viability, altered cell phenotype, and disrupted energy metabolism. In conclusion, this study contributes to the expanding body of recent research confirming the presence of MNPs in human airways. It underscores the potential adverse effects of MNP exposure on respiratory health, noting their accumulation in the bronchoalveolar segment of the human respiratory system, induction of phenotype changes, reduced viability, and alterations in regular cell metabolism.